Plaster of paris composition



Patented Apr. 7, 1931 UNITED STATES GEORGE H. A. RUBY, OF EAST GRAND RAPIDS, MICHIGAN PLASTER OF PARIS COMPOSITION No Drawing.

This invention relates to a cementitious composition in which the major proportion, by Weight, is of plaster of Paris with which a small percentage, by weight, of cotton linters is mixed. In many uses of plaster of Paris in building it is very desirable to mix therewith a material which will lighten the structure and permit it to be utilized to serve as a support for other things which may be nailed thereto, and for this purpose wood shavings and various other materials have been used. I have heretofore filed an application for patent wherein the use of cotton linters in the proportions of 1 percent to percent by weight are used with 99 percent to 75 percent by weight of plaster of Paris has been described and for a great many purposes these proportions are very satisfactory.

I have found, however, that the mixing of cotton linters with the plaster of Paris by labor not familiar therewith, where these amounts last mentioned are used is a difficult problem, particularly from the standpoint of 25 securing a uniform or homogeneous mixture, It is also desirable in some instances where ,strength is of more importance than lightness or cheapness that the percentage of cotton linters by weight shall be less than -1 percent of the total weight of the composition. This is particularly true with respect to the floors and ceilings of building structures.

The present invention, accordingly, is directed to a cementitious composition of plaster of Paris with which cotton linters are mixed, the whole being mixed with water to supply the water of crystallization necessary for setting and hardening of the mass,

in which, by weight, the cotton linters shall be less than 1 percent of the weight of the plaster of Paris used.

The mixing of the constituents of the composition is eflected by using a certain weight of plaster of Paris and mixing therewith less than 1 percent of its weight of cotton linters. In practice 15 pounds of cotton linters has been used with a ton of the plaster of Paris which is substantially three-fourths of 1 per cent by weight of cotton linters in the mix- Application filed March 11, 1929. Serial No. 346,255.

ture; and sufficient water is used to thoroughly wet the mass and supply the necessary water required for crystallizing and setting the plaster of Paris.

With these proportions of plaster of Paris and cotton linters a very uniform and homogeneous mixture of the linters with the mass of plaster of Paris may be obtained by use of unskilled labor, If a larger mass of the cotton linters is used the tendency of the linters to intertwine or hook together, or as it is sometimes called mat together, renders the homogeneous intermixture of the linters with the plaster of Paris very difficult to obtain and in the building of buildings the mixture of the cementitious mass necessarily takes place 011 the job and must be done with labor which can be readily obtained.

Even with this relatively small amount of the cotton linters used there is a very considerable admixture of the linters throughout the plaster of Paris. The cotton linters are very light in weight and form a relatively large bulk with'respect to the plaster of Paris even in the small percentage used and will readily intermix thoroughly with the plaster of Paris and at the same time have interengagement with each other sufiicient to provide a very homogeneous binding of the parts of the mass together. The cotton linters are stainless, do not absorb water and are exceptionally adapted for the purpose for which they are used in the composition described; while the relative large percentage of plaster of Paris used is an insurance that substantially all of the strength of a. wall made of solid plaster of Paris is obtained. 7

The invention is defined in the appended claims and is to be considered comprehensive of all variations from the specific detail set forth in the specification which are compre hended by the scope of said claims.

I claim:

1. A mass of hardened material consisting of plaster of Paris and less than 1 per cent of cotton linters, the mass being solidified through crystallization after the addition of water, the mass being strong and capable of holding nails.

2. A mass of hardened material consisting life? of plaster of Paris and three-fourths of 1 per cent of cotton linters, the mass being solidified through crystallization after the addition of Water, the mass being strong and capable of holdinfi nails.

In testimony W ereof I afiix my signature.

GEORGE H. A. RUBY. 

